Known in the art is a hybrid type vehicle designed to use one or both of an engine and an electric motor to drive the vehicle, wherein the engine is comprised of an engine provided with a variable compression ratio mechanism, a compression ratio is found whereby an overall efficiency considering an efficiency of the engine, an efficiency of the electric motor, an efficiency of a power transmission system, and all other efficiencies becomes the highest, and a compression ratio of the engine is controlled to the compression ratio giving this highest overall efficiency.